(1) Field of the Invention
The present invention relates to a process for the preparation of an allyl type amine. More particularly, the present invention relates to a process for the preparation of an allyl type amine which is broadly used as the starting material of a cationic polymer valuable as a coagulant or a medicine or agricultural chemical.
(2) Description of the Related Art
At the present, allylamine is prepared by reacting allyl chloride with ammonia (see U.S. Pat. No. 2,216,548 and U.S. Pat. No. 3,175,009). A process for preparing an allyl type amine by reacting a carboxylic acid ester of an allyl type unsaturated ether or allyl type unsaturated alcohol with ammonia in the presence of a combination catalyst comprising a palladium compound and a trivalent phosphorus or arsenic compound has been proposed (see Japanese Examined Patent Publication No. 49-20162). However, if allyl chloride or an allyl ester is used, hydrochloric acid or a carboxylic acid is produced with the synthesis of allylamine. Since this acid forms a salt with ammonia or the formed amine, the acid cannot be re-utilized. Moreover, in order to recover the amine, it is necessary to perform neutralization with an equimolar amount of a strong alkali. Furthermore, since a salt is formed, the process becomes complicated.
In the case where an allyl type alcohol is used as the starting material, water is formed as a by-product, and since this water does not react with the amine, the above-mentioned loss is not caused and the process becomes simple. However, the reactivity of the allyl alcohol is much lower than that of allyl chloride or the allyl ester. This can be confirmed from the difference between allyl acetate and allyl alcohol in the reactivity with dipropylamine shown in the following table (extracted from Research Disclosure, May 1978, page 35).
__________________________________________________________________________ Yield (%) of Allyl Amine Allyl Based on Sampling Temper- Allyl Compound/ Starting Allyl Time Solvent ature Catalyst compound Metal Ratio Compound (min.) __________________________________________________________________________ ethylene 35 (allyl PdCl).sub.2 / allyl 1942 99 30 glycol 4(BuO).sub.3 P acetate propylene 100 (allyl PdCl).sub.2 / allyl 100 82 220 glycol 4(BuO).sub.3 P alcohol __________________________________________________________________________
Although such conditions as the temperature, the allyl compound/catalyst molar ratio and the reaction time, adopted for allyl alcohol, are much advantageous over those adopted for allyl acetate, the yield is rather low in case of allyl alcohol even if the same catalyst is used. Thus, the reactivity of allyl alcohol is much lower than that of the carboxylic acid ester.
Another problem arises when allyl alcohol is used as the allyl source. Namely, the phosphine as the ligand is oxidized with the oxygen atom of allyl alcohol with advance of the reaction.
Atkins et al. synthesized allyldiethylamine from allyl alcohol and diethylamine in a catalyst system formed by using Pd(CH.sub.2 COCH.sub.2 COCH.sub.3).sub.2 as the starting complex and adding triphenylphosphine in an amount equimolar to palladium [Tetrahedron Letters, No. 43, pages 3821 to 3834 (1970)]. However, as pointed out hereinbefore, triphenylphosphine is gradually oxidized by allyl alcohol. Accordingly, precipitation of a black palladium compound is observed and the activity is not durable. This fact has been confirmed by experiments.
The reactivity of ammonia is lower than that of the amine, and none of catalysts are substantially effective for the reaction between allyl alcohol and ammonia. It has been confirmed that even if the reaction between allyl alcohol and ammonia is intended by using the catalyst of Atkins et al. under the same conditions, the reaction is hardly advanced. It also was found that if propylene glycol is used as the solvent and triphenylphosphine is added in excess, a yield of 6% is obtained by 2 hours' reaction, but deactivation of the catalyst is violent and further improvement of the yield is not attained. The reason is that oxidation of triphenylphosphine is caused, as pointed out hereinbefore. Accordingly, this catalyst system cannot be industrially used.
Furthermore, a process in which monoallylamine is synthesized from allyl alcohol and ammonia in the solid gas phase by using a phosphorus compound such as polyphosphoric acid as the catalyst has been proposed (see Japanese Unexamined Patent Publication No. 58-88342). However, also this process is defective in that the yield is poor and the practical utility is low.
As is apparent from the foregoing description, although the preparation of an allyl type amine by using an ally type alcohol as the allyl source is considered to be very advantageous, a process for preparing an allyl type amine by using an allyl type alcohol as the starting material, which can be industrially worked, is not established.